The present invention relates to commercial and/or residential heating and/or cooling systems and other indoor comfort systems, and is more particularly concerned with thermostats that are employed in managed properties, i.e., buildings and other properties in which individual spaces are occupied by tenants, i.e., families or companies. The invention is more specifically directed to property-management thermostat systems, i.e., landlord thermostats or lock-setting thermostats that are intended to prevent abuse of heating and/or air conditioning service that is provided to tenants. The heat or cooling may be provided from individual furnaces, heat pumps and air conditioners, from central heating and/or chilling facilities, or from thermal comfort units that are common to groups of tenant spaces within the managed property.
Wall thermostats are typically installed on an interior wall of a dwelling or commercial space to control the operation of a furnace, air conditioner, heat pump, or other environmental control equipment. The thermostat is intended to monitor the temperature of the room or other interior comfort space continuously, and to adjust the operation of the associated environmental control equipment to keep an interior comfort space parameter (e.g., temperature) within some range (e.g., 20° C.±0.5° C. or 68° F., ±1.0° F.). Other controls may be sensitive to other parameters, such as humidity or particulate level. The thermostat is typically connected to the furnace, air conditioner, heat pump or the like by means of a run of thermostat wires.
In commercial rental space or in residential rental properties such as apartments or condominiums, the landlord or property management company typically furnishes the heat and air conditioning, either through central furnace or boiler system for the heat and central chiller unit for air conditioning, or in some case using individual or localized furnaces and air conditioning units. In either case effective property management requires that the tenants not abuse the heating and cooling that is furnished so that costs and other problems may be kept under control.
In a typical existing property management thermostat system, which is discussed later in respect to FIG. 1 of the drawing, each tenant unit is provided with a thermostat to be mounted on the wall of the tenant space and is operatively coupled to the associated furnace, heat pump, and/or air conditioning unit. A building management technician installs the thermostat, and at the time of installation sets limits to the degree of heating or cooling that is permitted for the tenant. The typical such property management thermostat is configured as a lock-setting thermostat. The thermostat has an internal control circuit within the thermostat housing, and that is connected to a temperature sensor and to a signaling arrangement that connects thermostat power to the appropriate thermostat wires when there is a call for heat or a call for cooling. In addition, the lock-setting thermostat has an internal memory device, i.e., ePROM, that stores heating and cooling limit parameters that are set into the thermostat by the technician at the time of installation. That is, at installation, the technician may select a maximum heating set point, e.g., 68 degrees F., and a minimum air conditioning cooling setpoint, e.g., 74 degrees F. These are intended to place a limit to the thermostat settings that the tenant can select, so that in winter the tenant cannot set the heat setpoint above 68 degrees and in summer the tenant cannot set the cooling setpoint below 74 degrees. In the state-of-art systems, once the technician has entered the settings, these are permanently stored in the ePROM, and cannot later be changed, except by entirely replacing the thermostat. A disadvantage is that the current lock-setting thermostats cannot be re-programmed with new limits to accommodate a new tenant or to accommodate any tenant's change in circumstances, or to accommodate changes in local building codes.
Another problem encountered in managed property units is the tendency of some of the tenants to attempt to defeat the lock settings of the thermostat. This most often involves providing heat to the thermostat so that the local heat in the vicinity of the thermostat is much higher than the general room heat. For example, the tenant may place a lamp with an incandescent light bulb directly beneath the thermostat to heat it well above the established set point, so that the air conditioning will continue to furnish chilled air even when the air temperature is below the established cooling set point. Likewise, a tenant may hang a bag of ice on the thermostat to cool it well below the winter heating set-point so that the furnace or heater will continue to furnish heat even when the room air in the tenant space is warmer than the heat set-point. Current lock-setting thermostats lack any means of detecting any such attempt to defeat the thermostat, and cannot stop wasteful overheating or overcooling in these circumstances.